poke prompt by default

[Jose E. Marchesi]

Hello people.

I recently changed poke so the prompt used in the CLI can be customized
by the user: the CLI calls the Poke function pk_prompt to draw the
prompt.

At this point the default definition of that function is simply:

  fun pk_prompt = string:
  {
    return "(poke) ";
  }

This is the one I use instead (loaded from my .pokerc):

  fun pk_prompt = string:
  {
    var prompt = "(";

    prompt += get_endian == ENDIAN_BIG ? "big:" : "little:";
    try
      prompt += iohandler (get_ios);
    catch if E_no_ios
      {
        prompt += "poke";
      };

    return prompt + ") ";
  }

That gives me a nice prompt that reflects both the global endianness and
the currently selected IO space, like:

  (big:foo.o) _

I wonder:

1. It is easy for the user to write her own pk_prompt function, that may
   be as complex as desired.  However, the default version of the
   function may use the typical "format string" featuring predefined
   tags, such as "(%e:%i)" where %e is replaced by the current
   endianness and %i with the selected IO space or "poke" if no IO
   space.  This could ease a bit customizing prompts, but it would
   require documentation etc.  The question is: would supporting this be
   worth the effort and maintenance?

2. Is the default prompt the right default?  We are usually very
   conservative with defaults (no pretty-printing, plain output mode,
   etc) and that may give people the impression that poke is much more
   limited that it actually is.  Should we have a default like mine?

Thanks for the feedback.